1. Field of the Application
The present invention relates to metal working, and more particularly to mills for helical rolling of solids of revolution, as well as for die rolling.
The invention is especially suitable for application in rolling mills wherein the rolls mounted in a working stand are provided with a group drive.
2. Description of the Prior Art
A rolling mill roll line coventionally comprises an electric motor, a reducer, a pinion stand the output shafts of which are connected with the rolls of a working stand by means of spindles. The rolling mill roll line scheme mentioned above is universally adopted in the art, including the mills for helical rolling. A pinion stand usually comprises a split housing, the split parts of which are bolted together and are formed with recesses to receive therein one driven and two driving pinion shafts intended to impart rotation to the rolls mounted in a working stand. The transmission of rotation to the size rolls mounted in the working stand is effected by means of spindles, especially by the so-called universal spindles widely employed in modern rolling mills. This type of universal spindle comprises an intermediate shaft, two ends of which are provided with universal joints or Hooke's joints which consist of two forks interconnected with a cross piece. The universal spindles are provided in the rolling mill roll line to ensure reliable transmission of rotation moment to the working rolls, the efficiency of said spindles being rather high and their dimensions relatively small, with the axis of the spindle intermediate shaft forming together with the axis of a roll an angle variable within the range of 12 to 15 deg.
It has been found that uniform rotation of the working rolls is ensured when the transmission ratio of the spindle joints are equal to one. The term "transmission ratio of the spindle joints" is used herein to denote the ratio of the rotational speeds of the driven and driving shafts (of the working roll and of the pinion stand shaft). This will be possible if .alpha..sub.1 '=.alpha..sub.2 ' and .PSI.=.lambda., where:
.alpha..sub.1 ' is the angle of obliquity in a universal joint connected with the working roll shaft, i.e. the angle between the axis of the spindle intermediate shaft and the axis of a roll;
.alpha..sub.2 ' is the angle of obliquity in a universal joint connected with a pinion stand i.e. the angle between the axis of the spindle intermediate shaft and the axis of the pinion stand;
.PSI. is the angle of turn of the yokes of the spindle intermediate shaft, the yokes should be made to turn in the direction of swivel of the planes of the axes of the spindle joints;
.lambda. is the angle between the planes of the axes of the single universal couplings, positioned at a working and pinion stand.
The plane of the axes of the couplings is used to denote the plane which comprises two intersecting axes of a universal coupling (cf. "Vestnik Machinostroenia"/Engineering News, Moscow Publishers, 1965, No. 5, pp. 25-28).
It has been found in the course of theoretical and practical research that the provision of a group drive in rolling mills is by far not sufficient to ensure similar dynamic and kinematic characteristics for each roll in the zone of deformation, and such is essential for a reliable, efficient and high-quality process of rolling.